Differential effects of reduced contrast on perception of self-motion vs. object-motion

摘要

Several studies found that the speed of moving objects and patterns appears to decrease when contrast of the image is reduced (the "Thompson Effect"), suggesting that drivers may underestimate their speed in foggy conditions. However, a recent study, conducted on the road, found that drivers did not experience this illusion when contrast was reduced with diffusing filters (Owens, Wood, & Carberry, 2010, Perception). We conducted a two-part experiment to examine the differential effects of reduced contrast on perception of object-motion vs. self-motion. For object-motion, participants matched the speed of rotating disks of variable contrast; for self-motion, they estimated the speed of travel perceived in video clips of driving on a country road. Like the Thompson Effect, our results showed the disks appeared to rotate more slowly when contrast decreased. This effect was not found, however, for estimates of speed in the driving videos. These findings suggest that different neural pathways mediate perception of self-motion vs. object-motion.